Airplanes frequently pick-up objects from the ground, for instance advertising banners which they tow, for instance, along a beach or other crowded areas.
When planes pull the advertising banners they must take off without them and then pick them up. This is done with a hook hanging from a rope that hangs from the tail of the plane. If the plane gets too low, the hook could hit the ground. If the hook gets caught on something on the ground, the cable could be over-stressed and break. If the cable doesn't give, the tail could be over-stressed and cause structual failure to the plane. The more common thing to happen is for the hook to spring back up to the plane and get caught in the tail surfaces. If this happens, the plane will most certainly be out of control. Many pilots and planes have been lost this way.